Conventionally, there is known a disk device having a loading mechanism that carries a disk-shaped information recording medium (hereinafter, referred to as a disk medium) between a loading position inside the device and an unloading position outside the device. Such a disk device is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2002-93013 (Page 7, FIGS. 2-4). In such a disk device, a turn table for rotating the disk medium and an optical pickup or the like are mounted on a base (hereinafter, referred to as a middle base) that is movable in vertical direction, in order to prevent the interference with the disk medium being carried.
In such a conventional disk device, a pair of shaft portions are formed at both sides of the middle base, and the shaft portions fit in supporting portions formed on a device base of the disk device. The supporting portions are semi-circular cut-outs that open upward, and the shaft portions fit in the supporting portions from above. Further, urging mechanisms are provided in the vicinities of the supporting portions, which urge the shaft portions so that the shaft portions are not dropped out of the supporting portions. As constructed above, there is a problem that, when the disk device receives an impact caused by the falling of the disk device or the like, the supporting portions or the urging mechanisms may be deformed by the impact, and therefore the shaft portions may be dropped out of the supporting portions, with the result that a whole unit (including the turn table and the optical pickup supported or the like) supported by the middle base may be dropped out of the device base of the disk device.